1. Field of the Invention
The invention in general relates to a vertical sensing system for a structure, and more particularly to a system which provides an output signal indicative of structure tilt, while eliminating any output signal which may be due to a lateral movement of the structure.
2. Description of Related Art
It is often desired to obtain an indication of the pitch or tilt angle of a structure in order to initiate a corrective action, if required. By way of example, various deployable radar systems include a vertical tilt sensor cooperative with the radar antenna to allow radar height measurements to be corrected for static as well as dynamic tilt of the antenna structure during operation.
A static tilt of the antenna from a pure vertical orientation may be present due to the fact that the antenna is not perfectly levelled each time it is deployed. Such static tilt may also change during operation due to settling of the antenna. Dynamic tilt of the antenna results from deflections in the antenna structure caused by wind forces.
In these radar systems, the tilt sensor will provide an output signal indicative of antenna tilt to correct the radar measurements of the height to a distant target, which in the absence of such correction would result in an erroneous target indication.
A problem arises however in that the fast response time of the tilt sensor also makes it sensitive to dynamic horizontal lateral movements which also result from the wind forces. This horizontal translation of the antenna has no significant effect on radar height performance and accordingly any translation detected by the sensor will result in erroneous correction of the height measurements. The present invention provides a solution to this problem.